DESCRIPTION JPS5723097

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DESCRIPTION JPS5723097
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an example of a
conventional moving coil type vibration pickup, FIG. 2 is a sectional view showing one
embodiment of a moving coil type vibration pick amplifier according to the present invention,
FIG. Is a perspective view of the bobbin 4, FIG. 4 is a plan view of the suspension 6a or 6b, and
FIG. 5 is a view showing the vibration characteristic of the vibration pickup. Explanation of
symbols of major parts, 1 ... magnet 2 ... pole piece 3 ... yoke 4 ... bobbin 5: movable coil 6.6a, 6b
suspension 7 ° 8 ... casing, 9 ... spacer.
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a moving coil type
vibration pickup having a moving coil provided in a magnetic circuit. The moving coil type
vibration pickup is configured to detect mechanical vibration as relative movement of the
magnetic circuit and the movable coil, and to obtain a vibration detection signal by current
generated in the movable coil. FIG. 1 shows an example of a conventional moving coil type
vibration pickup, and in particular, a cross section in a plane including the central axis of a
movable coil. In the figure, a magnetic circuit is formed by the magnet 1, the pole piece 2 and the
yoke 3, and the bobbin 4 is wound in an annular magnetic gap formed by the pole piece 2 and
the yoke 3 of the magnetic circuit. The movable coil 5 is provided. Further, an annular support
member or suspension 6 is connected to the upper end of the bobbin 4. The outer peripheral
portion of the suspension 6 is supported by casing members 7 and 8 holding the magnetic
circuit, and supports the bobbin 4 and the movable coil 5 so as to be movable relative to the
magnetic circuit in the axial direction. The moving coil type vibration pink-up 2 has the abovedescribed structure, and the mechanical vibration transmitted from the outside through the
casing members 7 and 8 is an electric current generated by the relative movement of the
movable coil 5 and the magnetic circuit. It is converted to an electrical signal. The frequency
characteristics of vibration detection are determined mainly by the mechanical loss
characteristics of the vibration system determined mainly by the weight of the bobbin 40 and the
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rigidity of the suspension 6, but the desired vibration detection characteristics can be obtained
by appropriately selecting each of the above values. It is possible to get Furthermore, such a
moving 'coil type vibration pink amplifier has directivity in the central axis direction of the
movable coil 5, and the vibration system follows the vibration in such a direction. However, in the
case of the conventional moving coil type vibration pickup, since a single substantially flat
suspension 6 is used, the suspension sufficient for movement of the vibration system other than
the direction coincident with the central axis of the movable coil 5 For example, the vibration
detection performance may be deteriorated because the rigidity of the vibration system can not
be obtained and, for example, inclination of the vibration system occurs. The present invention
aims to ameliorate the above-mentioned drawbacks in the conventional moving coil type
vibration pink 3-up, and to improve the rigidity of the suspension in directions other than the
central axis direction of the vibration system and to improve the vibration detection
characteristics. The moving coil type vibration pickup according to the present invention is
characterized in that a pair of suspensions are provided in a direction perpendicular to the
central axes of the movable coil and the bobbin to increase the rigidity of the suspension in any
direction other than the desired vibration direction of the vibration system. is there.
Embodiments of the present invention will now be described in detail with reference to the
drawings. FIG. 2 is a cross-sectional view of a moving coil type pink-up in the same plane as FIG.
1 showing one embodiment of the present invention. In the figure, the magnetic circuit of the
vibration pickup comprises the magnet 1, the pole piece 2 and the yoke 3 as in the prior art, and
the movable coil 5 is disposed in the magnetic gap of the magnetic circuit. Here, the bobbin 4 for
holding the movable coil 5 is formed with seven runge-like projections 4α on the outer
periphery of the upper end portion thereof, and a pair of suspensions 6a and 6b are connected 4
to the upper and lower surfaces of the projections 4α. In addition to the casing members 7 and
8, an annular spacer 9 having the same thickness as the projection 4α of the bobbin 4 is used to
hold the outer periphery of the suspensions 6α and 6b. Suspension 6α and 6b are supported.
Although the moving coil type vibration pickup according to the present invention is thus
designed to obtain sufficient rigidity of the suspension by supporting the vibration system using
a pair of suspensions provided parallel to each other, as shown in FIG. In FIG. 4, the shape of the
bobbin 4 is illustrated, and in FIG. 4, a plan view of the suspension 6α or 6b is illustrated. By
using the bobbin 4 having such a flange-like projection, the same suspension 6α or 6b as in the
prior art can be used, and the rigidity of the suspension can be easily increased by the structure
O, as shown in FIG. An example of a vibration characteristic at the time of vibrating a moving coil
type | mold vibration pinkup by this invention by fixed acceleration of 980 dyne / 5ee2 is shown
in figure by 5-. Also, in the figure, the curve indicated by the broken line shows the vibration
characteristics of the conventional moving coil type vibration pick amplifier having a single
suspension, and particularly in the case of the vibration pickup according to the present
invention, around the resonance frequency fo. It is understood that the characteristics are
significantly improved and the suspension system supports the vibration system almost ideally.
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Also, dips of the curve seen in the case of the conventional vibration pink-up indicate a plurality
of resonances of the imaging system caused by the vibration system moving in a direction other
than the direction along the central axis, and this mechanical force In order to prevent resonance,
a high processing accuracy is required so that the suspension has the same rigidity in all parts,
but according to the present invention, resonances other than in the axial direction of the
vibration system can be easily removed. It is characterized in that superior vibration detection
performance can be obtained easily as compared with.
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